The invention relates to an actuation mechanism for a wedge-actuated drum brake, in particular for commercial vehicles, to a wedge-actuated drum brake and to an actuation system for wedge-actuated drum brakes.
Drum brakes for commercial vehicles are known in the prior art. They customarily comprise an actuator unit which can be formed by a pneumatically or hydraulically operated brake cylinder, an actuating unit/spreading unit for displacing a brake element which is equipped with a brake lining, and a transmission unit for transmitting a force from the actuator unit to the actuating unit. In the case of wedge-actuated drum brakes, a brake lining carrier having a brake lining mounted thereon is displaced radially outward and pressed against the inner face of a rotating brake drum by a wedge-shaped, longitudinally displaceable actuating element. Here, depending on the existing space, the axis formed by the wedge with the brake cylinder extends either parallel or obliquely to the axis of the wheel to be braked. The transmission element arranged between the brake cylinder and the actuating element can be dimensioned such that, depending on the existing structural frame, the brake cylinder is arranged at a favorable position. The dimensioning of the brake cylinder means that the installation of such an actuation mechanism in certain assemblies which have only a limited clearance is barely possible, if at all. It is known from DE 10 2013 215 850 A1, for example, to solve such installation problems by providing a deflection device which deflects the force to be transmitted from an actuator unit to the actuating element from a first into a second direction. This change of direction is intended to make possible different positionings, in particular of the actuator unit. However, it is problematic here that mechanical deflection systems of this type are relatively difficult to construct and the spreading units used here require an additional and/or solid fastening to the axle in order to absorb the vibrations and accelerations (unsprung masses). Furthermore, a separate brake cylinder is required for each brake unit, which can lead to space problems in particular in the case of swing axles.
It is therefore an object of the present invention to provide an actuation mechanism, a wedge-actuated drum brake and an actuation system whereby the aforementioned problems can be eliminated.